1. Field of the Invention
The present invention relates to a waste-toner collecting device for collecting non-transferred toner as waste toner remaining on an image carrier such as a photosensitive drum, a photosensitive belt, and an intermediate transfer belt, and to a process cartridge and an image forming apparatus provided with the same.
2. Description of the Related Art
In an electrophotographic image forming apparatus such as a copier, a printer, a facsimile, or a multifunction product of these devices, there has been conventionally known a technology for removing non-transferred toner (residual toner) deposited on an image carrier such as a photosensitive drum by a cleaning unit, conveying the non-transferred toner collected by the cleaning unit toward a waste-toner collecting device (a waste-toner collecting box or a waste-toner tank) via a conveying path, and collecting and storing the collected toner as waste toner inside of the waste-toner collecting device (e.g., see Japanese Patent No. 4135415 and Japanese Patent Application Laid-open No. 2009-80473).
When the waste-toner collecting device is full of the waste toner collected and stored inside thereof, the waste-toner collecting device is taken out from the body of the image forming apparatus and is replaced with new one. Here, because the waste toner (non-transferred toner) collected into the waste-toner collecting device is toner after it is used in a series of image forming processes, the waste toner has a low fluidity as compared with that of fresh toner before being used, and thus it is difficult to be uniformly accumulated inside the waste-toner collecting device and it is therefore easy to be locally accumulated. Once the waste toner is locally accumulated in the waste-toner collecting device, even though the waste toner in the waste-toner collecting device is not in a full state, a full-state detection sensor for detecting a full state of waste toner inside thereof incorrectly detects the state, which causes inconvenience that replacement-maintenance of the device is frequently required. Therefore, the waste-toner collecting device is generally provided with a leveling member (conveying member, screw auger) for leveling the waste toner accumulated inside thereof. More specifically, the waste toner collected, stored, and accumulated in the waste-toner collecting device is leveled by the leveling member to be uniformly accumulated inside of the waste-toner collecting device.
In the conventional waste-toner collecting device, an operating efficiency of the leveling member is low, and power consumption required for driving the leveling member may thereby be increased, or variations may occur in a leveled state of the waste toner inside thereof being leveled by the leveling member.
More specifically, the leveling member in the waste-toner collecting device is driven in association with an image forming operation performed on the image carrier. In other words, the drive of the leveling member is started at the same time when the image forming operation on the image carrier is started, and the drive of the leveling member is stopped at the same time when the image forming operation on the image carrier is finished. However, an amount of waste toner conveyed from the cleaning unit toward the waste-toner collecting device is largely different depending on an image area of an image formed on the image carrier. Therefore, if settings of driving conditions of the leveling member are uniformly fixed, power consumption required for driving the leveling member may be increased, or variations may occur in the leveled state of the waste toner in the device being leveled by the leveling member. More specifically, once the driving condition of the leveling member is set according to a large amount of the waste toner collected in the waste-toner collecting device, then the driving condition of the leveling member is more than required and the power consumption required for driving the leveling member is increased when a small amount of the waste toner is collected. On the other hand, once the driving condition of the leveling member is set according to a small amount of the waste toner collected in the waste-toner collecting device, then the leveling of the waste toner in the device is insufficient when a large amount of the waste toner is collected.